Pacific Ocean Regulates Global Climate

A new paper presented in Nature Geoscience show a realistic evolution of global mean surface temperature since 1900 with the help of advanced computer simulations. The study distinguishes a clear anthropogenic (human caused) warming by removing natural variability, regulated mainly by the Pacific Ocean.

Plotted raw temperature data show a rise of temperatures in a nonlinear fashion, with steeper increases over the past 50 years. When removing natural variability, warming and cooling of the Pacific Ocean, the rise in global mean surface temperatures show a more linear increase with an acceleration in the 1960s. The Pacific Ocean thus plays a key role in regulating global climate, for example, by having a cooling effect between 1998-2014 (also known as the “hiatus”).

While raw data show a warming of 0.9 °C between 2010-2014 relative to 1900 Kosaka & Xie’s calculations yields a much higher anthropogenic warming of 1.2 °C after correcting for the natural variability. Because the Pacific had a cooling effect during this period anthropogenic warming have been underestimated. When the Pacific turns from carbon sink to source warming is likely to accelerate. This is the scary thing about natural systems, they behave in dynamic, nonlinear fashion, amplifying or dampening forcings.